Android icon for androidintent question type in vellum

Related PR: https://github.com/dimagi/Vellum/pull/60
![screen shot 2013-05-22 at 9 36 51 am](https://f.cloud.github.com/assets/716573/548487/fea00412-c2e4-11e2-80f5-1768da437f37.png)